2015+ IRS 13" rear brake caliper

[erstanl]

So, I am filling my brakes the other day, use my Mityvac vacuum bleeder. I have all the lines full, and the pedal is getting pretty firm. I reach my leg into the cockpit and pump the brake a few times. Feels really good. I do a walk around, and see the passenger rear caliper is puking brake fluid out all over the pads and rotor. I confirmed it is NOT coming from the bleeder nor the brake line itself. Looks like its coming from the slave cylinder. Anyone ever run into this? I am using a 2004 master cylinder, and a 2004 hydroboost (which wasnt in play, as the engine isnt running at the moment). Anyone have issues here besides me?

[Hoooper]

Pull the caliper and check the piston, sounds like the piston seal is leaking.

[erstanl]

I pulled the caliper out, confirming that the bleeder and banjo were dry. Those seem to be sealing up just fine. Looks like it is the piston seal.

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The seal (or maybe a boot?) actually looks good, meaning its still soft, no visible tears. Although, I haven't attempted to pull the piston yet either. Any ideas on whats going on here?

[Hoooper]

Im not familiar with that caliper but to me it looks like the seal is all the way out. Did you or someone else happen to press the brake with fluid in the lines before the rotor and pads were installed?

[erstanl]

Hooper, negative. Im not an expert, but I know enough to understand what happens when you do that :)

[michael everson]

Something looks off. either that's the piston seal right behind the boot or the boot is no seated in its groove. You need to take it parts and see whats going on.
Mike

[erstanl]

Michael, It seems like the boot is seated in the caliper, and barely seated around the piston. The boot however is completely full of fluid. Like the seal is just not there, or like you said, jammed up behind the boot. FF is sending me out a new caliper today, so I will tear into this one and see what the story is.

[CraigS]

If the seal is installed properly you could run w/o the boot. All it does is keep out dust and debris to prevent long term damage. One way or the other your seal isn't working. I am glad FFR is sending another caliper.

[chuckster]

The photo also shows quite clearly what an effective paint stripper brake fluid is. Lol

[erstanl]

So for the record, I pulled it apart carefully. The boot was still seated firmly into the housing. Once that was out I unscrewed the piston. The seal was still in place, no damage, no scarring, no scuffing etc. It looked new.

In the bottom of the piston though, there is some kind of valve that has a rubber seal as well. It apparently vents into the piston groove where the boot seats. Not sure if this is where it was leaking or not. No smoking gun here.

[VAHokie]

Same thing happened to me. Rear PS caliper piston on the 13" rear break kit was leaking fluid. FFR was quick to send out a replacement and glad to hear they did for you too.